I know perfs are important to you here, but another thought is this stamp a forgery..??
Here is one of mine compared to your Scott 12
Now I did a perf count on your Scott 12 and my authentic Scott 12.
My stamp has 13 perfs across the bottom...Yours has 12...
This could mean reperfed stamp or a forgery.
Scott 12's are not usually known for wide borders, which could be reperfed...Look at the bottom of your stamp...If it was nicely reperfed, which would mean it had a very LARGE border...I am leaning towards a forgery..Just my opinion.